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List:       linux-arm-kernel
Subject:    Re: Problems invalidating entire data TLB (in Xscale)
From:       Robert Schwebel <robert () schwebel ! de>
Date:       2003-11-30 22:17:47
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Javier, 

On Mon, Nov 24, 2003 at 12:23:25PM +0100, Javier Álvarez wrote:
> Im using the BK tree from David Brownell -> linux 2.6.x-test9 with PXA
> / USB support.
> 
> Im trying to execute the kernel in a CSB-226 ( based in Xscale PXA250
> processor).

Unfortunately, I didn't have time to update our CSB226 support (included
in the -ptx series) to support 2.6, but I'll do it soon because of a
customer project. 

> When I am setting the architecture my machine is hanging up.
> 
> The last line of kernel Im executing is the line which is invalidanting
> entire data TLB:
> 
> "  asm("mcr%? p15, 0, %0, c8, c5, 0" : : "r" (zero));    "
> 
> Any idea? I see the Xscale doc and this instruction is ok. Then, does
> anybody know why is hanging my machine up?

Do you run this with or without JTAG debugger support? I'm not sure
about this special register access (don't have the sources available
here at home at the moment) but there have been 'hangs' running under
JTAG control with the 2.4 code when accessing certain cp15 registers.
The effect was that the machine stoped at the instructions and you had
to add a 'go' on the BDI command line, but after that the machine just
kept on running. Without having the JTAG cable connected it worked fine. 

If you want to have a look at my workaround see the latest -ptx patch on
our homepage.

Robert
-- 
 Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
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